[Clinical significance of skeletonization dissection for No.12 lymph nodes after neoadjuvant therapy in advanced...

Objective: To explore the clinical significance of skeletonized lymph node dissection of No.12 lymph nodes after neoadjuvant therapy in patients with advanced gastric cancer. Methods: For this retrospective case-cohort study we collected data from patients with advanced gastric cancer who underwent neoadjuvant chemotherapy and D2 or more extensive curative resection including No.12 lymph node dissection at the First Affiliated Hospital of Sun Yat-sen University from January, 2011 to December, 2022. Patients were divided into two groups based on whether they received skeletonized dissection of No.12 lymph nodes: 177 cases were in the skeletonized group, and 55 cases were in the nonskeletonized group. The differences of prognosis between the two groups were compared, and logistic regression models were used to analyze the factors affecting No.12 lymph node metastasis in the overall cohort and No.12b or No.12p lymph node metastasis in the skeletonized group. Results: A total of 232 patients were included, with 84 females (36.2%) and 148 males (63.8%), with an average age of 56.4±11.6 years. The proportion of female and ycT4 patients was significantly higher in the skeletonized group than in the nonskeletonized group (both P<0.05). Among all 232 patients, No. 12a metastasis occurred in 14 cases (6.0%). In the skeletonized group of 177 patients, No. 12b and No. 12p metastases were observed in 6 patients each (3.4%), and 4 patients had concurrent metastases in both No. 12b and No. 12a. The 5-year overall survival (OS) rates were 45.5% in the skeletonized group and 42.8% in the nonskeletonized group, with no statistical difference (HR=0.755, 95%CI: 0.488-1.168, P=0.580). The 5-year disease-free survival (DFS) rates were 39.8% and 41.0%, respectively, also with no statistical difference (HR=0.775, 95%CI: 0.513-1.172,P=0.584). 5-year OS for patients without No.12 lymph node metastasis was 48.8%, which was higher than the 15.9% for those with metastasis (HR=0.349, 95% CI: 0.209-0.584, P=0.003). Additionally, the 5-year DFS for those without metastasis was 44.3%, significantly higher than the 5.7% for those with metastasis (HR=0.444, 95%CI: 0.276-0.716, P<0.001). For patients without No. 12b or No. 12p lymph node metastasis, the 5-year OS was 47.6%, and the 5-year DFS was 42.3%, both of which were significantly higher than the 16.7% and 8.3% for those with No.12b or No. 12p lymph node metastasis, respectively (HR=0.353, 95%CI: 0.183-0.681, P=0.005; HR=0.457, 95%CI: 0.244-0.855, P=0.006). Multivariate analysis showed that more advanced ypN stage (OR=3.908, 95%CI:1.638-9.323, P=0.002) and tumor location in the lower stomach or whole stomach (OR=3.533, 95%CI: 1.312-9.511, P=0.012) were independent risk factors for No.12 lymph node metastasis and also for No.12b and No.12p lymph node metastasis (OR=2.426, 95%CI: 1.212-4.856, P=0.012 and OR=4.908, 95%CI:1.182-20.373, P=0.028, respectively). Conclusion: Patients with advanced gastric cancer who have more advanced ypN stage and tumor location in the lower stomach or whole stomach have a higher risk of No.12b and No.12p metastasis and thus require further skeletonized lymph node dissection of No.12.